The Office of the County Controller is the Chief Financial Office and Chief Administrative Office of Montcalm County. The department is responsible for various financial, personnel, administrative, and managerial functions of county government.

The department is responsible for the county accounting function, personnel administration, payroll processing, budget preparation and administration, fiscal policy, development and maintenance, purchasing, insurance administration, administrative support to the Board of Commissioners, grant administrator, information systems management, county park reservations, and general management functions of county government. The office generates no significant amount of revenue, except the Controller, may actively seek grants and coordinate grant applications.